Screaming Penguin - Source Does Matter

Put down that cup of decaffeinated coffee! In an attempt to justify their addiction, researchers in Israel have shown that caffeine makes existing brain cells swell and new ones grow, which may be responsible for better memory and learning capability. This result would not be surprising because of the well known effect of caffeine to increase mental awareness. Mens Fitness Magazine has also reported that caffeine bolsters the intensity of your workout and is a natural diuretic (makes you pee so you don't retain water). They also suggest taking it only in the morning so that it doesn't prevent you from getting enough deep sleep, which lack of has ironically been linked to memory loss.